View source for Specific Process Knowledge/Characterization/Optical characterization

==Ellipsometer VASE and Ellipsometer M-2000V [[Image:section under construction.jpg|70px]]==
[[image:Ellipsometer_VASE_image.JPG|275x275px|right|thumb|Ellipsometer VASE: positioned in cleanroom 2]]

The ellipsometer VASE is a VASE (Variable Angle Spectroscopic Ellipsometry) ellipsometer from J.A. Woollam Co., Inc. <br/>
The ellipsometer M2000V is an in-situ ellipsometer from J.A. Wollam Co., Inc. this is positioned on the Sputter System Lesker instrument for in-situ measurements.

Ellipsometry is a very sensitive characterization technique which can be used to determine thin film layer thicknesses and/or optical constants. It sends in polarized light on the surface at different angles and measures the change in polarization state of the reflected light. 

It is especially good for thin films in the thickness range of a few nanometers to a few microns. The layer should be transparent to light in the usable wavelength range for the thickness to be determined. Large roughness (>40nm) and features within the field of view can cause the measurement to fail. 

Ellipsometry is an indirect measurement so a model has to be fit to the data in order to obtain the film thickness and optical constants. To learn more about ellipsometry you can take a look at the [http://www.jawoollam.com/tutorial_1.html tutorial] provided by the J. A. Woollam Co.

'''The user manual(s), quality control procedure(s) and results, user APV(s), technical information and contact information can be found in LabManager:''' 
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[http://labmanager.danchip.dtu.dk/function.php?module=Machine&view=view&mach=316 LabManager page for Ellipsometer VASE] <br/>
[http://labmanager.danchip.dtu.dk/function.php?module=Machine&view=view&mach=261 LabManager page for Ellipsometer M-2000V]
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===A rough overview of the performance of the Ellipsometers===

{| border="2" cellspacing="0" cellpadding="2" 

!colspan="2" border="none" style="background:silver; color:black;" align="center"|Equipment 
|style="background:WhiteSmoke; color:black"|<b>Ellipsometer VASE</b>
|style="background:WhiteSmoke; color:black"|<b>Ellipsometer M-2000V</b>
|-
!style="background:silver; color:black;" align="center" width="60"|Purpose 
|style="background:LightGrey; color:black"| 
|style="background:WhiteSmoke; color:black"|
*Measure thinfilm thicknesses and optical constants for single and multilayer optical transparent thinfilms.
*Measure opticals constants for bulk material 
|style="background:WhiteSmoke; color:black"|
*Measure growth rate of depositions done in the Sputter System Lesker.
*Measure thinfilm thicknesses and optical constants for single and multilayer optical transparent thinfilms.
|-
!style="background:silver; color:black" align="center" valign="center" rowspan="2"|Performance
|style="background:LightGrey; color:black"|Films that can be examined
|style="background:WhiteSmoke; color:black"|
Any film that is transparent to the light in the given wavelength range
e.g.:
*Silicon Oxide
*Silicon nitride
*PolySilicon
*Resists
*Polymers
*Very thin layers of metals
*and many more
|style="background:WhiteSmoke; color:black"|
Any film that is transparent to the light in the given wavelength range
e.g.:
*Silicon Oxide
*Silicon nitride
*PolySilicon
*Resists
*Polymers
*Very thin layers of metals
*and many more
|-
|style="background:LightGrey; color:black"|Film thickness range
|style="background:WhiteSmoke; color:black"|
*~20Å to 2 µm (depending of the material)
|style="background:WhiteSmoke; color:black"|
*~20Å to 2 µm (depending of the material)
|-
!style="background:silver; color:black" align="center" valign="center" rowspan="4"|Process parameter range
|style="background:LightGrey; color:black"|Wavelength range
|style="background:WhiteSmoke; color:black"|
*210nm-1690nm
|style="background:WhiteSmoke; color:black"|
*370nm-1000nm
|-
|style="background:LightGrey; color:black"|Incident angle range
|style="background:WhiteSmoke; color:black"|
*45-90 degrees
|style="background:WhiteSmoke; color:black"|
*One fixed angle - about 70 degrees
|-
|style="background:LightGrey; color:black"|Beam size
|style="background:WhiteSmoke; color:black"|
*2mm (spot size on sample depends on the angle)
|style="background:WhiteSmoke; color:black"|
*5mm (spot size on the sample depends on the angle)
|-
|style="background:LightGrey; color:black"|Mapping facility
|style="background:WhiteSmoke; color:black"|
*Can make wafermaps on up to 150mm wafers
|style="background:WhiteSmoke; color:black"|
*No mapping facility
|-
!style="background:silver; color:black" align="center" valign="center" rowspan="2"|Accessories
|style="background:LightGrey; color:black"|Focusing optics
|style="background:WhiteSmoke; color:black"|
*Focus lenses can be applied, reduces the beam diameter to 125µm
|style="background:WhiteSmoke; color:black"|
*No focusing lenses
|-
|style="background:LightGrey; color:black"|Transmission stage
|style="background:WhiteSmoke; color:black"|
*Extra stage for transmission measurements
|style="background:WhiteSmoke; color:black"|
*Base for ex-situ measurements, transmission data can be done by holding the sample up agains the detector
|-
!style="background:silver; color:black" align="center" valign="center" rowspan="2"|Substrates
|style="background:LightGrey; color:black"|Batch size
|style="background:WhiteSmoke; color:black"|
*One sample at a time smaller than 150mm (ask if you have anything larger)
|style="background:WhiteSmoke; color:black"|
*One sample at a time, any sample size that goes in the Sputter System Lesker
|-
| style="background:LightGrey; color:black"|Allowed materials
|style="background:WhiteSmoke; color:black"|
*Any material that does not leave residuals on the stage and that does not evaporate
|style="background:WhiteSmoke; color:black"|
*Any material that may go into the Sputter system Lesker
|- 
|}


{| border="2" cellspacing="0" cellpadding="10" 
|-
!style="background:silver; color:black;" align="left"|Purpose 
|style="background:LightGrey; color:black"|Film thickness measurements and optical characterization of optically transparent thin films||style="background:WhiteSmoke; color:black"|
*Measurement of (multi layer) film thickness (only one unknown layer)
*Optical constants
|-
!style="background:silver; color:black" align="left"|Performance
|style="background:LightGrey; color:black"|Thin film materials that can be measured||style="background:WhiteSmoke; color:black"|
Any film that is transparent to the light in the given wavelength range
ex:
*Silicon Oxide
*Silicon nitride
*PolySilicon
*Photoresists
*SU8
*Other polymers
*Very thin layers of metals (<20 nm)
*and many more
|-
|style="background:silver; color:black"|
|style="background:LightGrey; color:black"|Film thickness range
|style="background:WhiteSmoke; color:black"|
*~20Å to 2 µm (depending of the material)
|-
!style="background:silver; color:black" align="left"|Process parameter range
|style="background:LightGrey; color:black"|Wavelength range
|style="background:WhiteSmoke; color:black"|
*300-950 nm
|-
!style="background:silver; color:black" align="left"|Substrates
|style="background:LightGrey; color:black"|Batch size
|style="background:WhiteSmoke; color:black"|
*One sample at a time - all sample larger than  about 1x1 cm<sup>2</sup>sizes up to about 6"
|-
|style="background:silver; color:black"|
|style="background:LightGrey; color:black"|Substrate material allowed
|style="background:WhiteSmoke; color:black"|
*In principle all materials
|- 
|}



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==Filmtek 4000==
[[image:Filmtek.JPG|275x275px|right|thumb|FilmTek 4000: positioned in cleanroom 2]]
FilmTek 4000 is a computerized film thickness measurement and material characterization system. This system combines fiber-optic spectrophotometry with advanced material modeling software to provide an affordable and reliable tool for the simultaneous measurement of film thickness, index of refraction, and extinction coefficient

Normal incidence and polarized 70 degree reflection data is collected and used to calculate thickness and index of refraction of the measured film using SCI’s patented Differential Power Spectral Density (DPSD) technique. Absolute reflection data is obtained by comparing sample data to the measured reflection of a known reference sample, typically a silicon wafer with a thermally grown thin oxide (~63 nm) film.

The spectrophotometer scans the sample over a predefined range of wavelengths. The software generates a reflection spectrum based on a previously stored reference scan, and then performs a regression on the unknown parameters to fit the simulated reflection and power spectral density to the observed values. The resulting thin film parameters along with the measured and modeled spectra are then displayed for the user to examine.
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===An overview of the performance of the FilmTek===

{| border="2" cellspacing="0" cellpadding="10" 
|-
!style="background:silver; color:black;" align="left"|Purpose 
|style="background:LightGrey; color:black"|Film thickness measurements and optical characterization of optically transparent thin films||style="background:WhiteSmoke; color:black"|
*Measurement of (multi layer) film thickness (only one unknown layer)
*Optical constants
*Surface roughness
|-
!style="background:silver; color:black" align="left"|Performance
|style="background:LightGrey; color:black"|Thin film materials that can be measured||style="background:WhiteSmoke; color:black"|
Any film that is transparent to the light in the given wavelength range
ex:
*Silicon Oxide
*Silicon nitride
*PolySilicon 
*Photoresists
*SU8
*Other polymers
*Very thin layers of metals (<20 nm)
*and many more
|-
|style="background:silver; color:black"|
|style="background:LightGrey; color:black"|Film thickness range
|style="background:WhiteSmoke; color:black"|
*<100 Å to 250 µm (depending of the material)
|-
!style="background:silver; color:black" align="left"|Process parameter range
|style="background:LightGrey; color:black"|Wavelength range
|style="background:WhiteSmoke; color:black"|
*400-1000 nm
|-
!style="background:silver; color:black" align="left"|Substrates
|style="background:LightGrey; color:black"|Batch size
|style="background:WhiteSmoke; color:black"|
*One sample at a time - all sample larger than 5x5 mm<sup>2</sup>sizes up to 6"
|-
|style="background:silver; color:black"|
| style="background:LightGrey; color:black"|Substrate material allowed
|style="background:WhiteSmoke; color:black"|
*In principle all materials
*Only pure silicon, silicon oxides, silicon nitrides and quartz may be in direct contact with the surface of the stage. If you have metals, III-V materials or polymers on the back side of the substrate the please mount your sample on a silicon carrier wafer.
|- 
|}



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==Prism Coupler==
[[image:Prism_coupler.jpg|300x300px|right|thumb|Prism coupler: positioned in cleanroom 2]]
The Prism coupler is a Metricon model 2010 Prism Coupler. It is an old system from 1991 but the system with a few modifications is still beening manufactured today. It is still a very easy and relaible method of determining thickness and refractive index.
The prism coupler uses an optical waveguide technique to determine the thickness and refractive index of a thin film. To learn more about the theory of measurement please see the homepage of [http://www.metricon.com Metricon]

It is especially good for making fast accurate measurements of dielectric thin films with n<2.02 and  a thickness range of 1 µm to about 15 µm.  
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===An overview of the performance of the Prism Coupler===

{| border="2" cellspacing="0" cellpadding="10" 
|-
!style="background:silver; color:black;" align="left"|Purpose 
|style="background:LightGrey; color:black"|Film thickness measurements and optical characterization of optically transparent thin films||style="background:WhiteSmoke; color:black"|
*Measurement of film thickness
*Optical constants
|-
!style="background:silver; color:black" align="left"|Performance
|style="background:LightGrey; color:black"|Thin film materials that can be measured||style="background:WhiteSmoke; color:black"|
Film with a refractive index of less than 2.02 and that are transparent to the light in the given wavelength range
ex:
*Silicon Oxide
*Silicon nitride
*polymers
|-
|style="background:silver; color:black"|
|style="background:LightGrey; color:black"|Film thickness range
|style="background:WhiteSmoke; color:black"|
*~1µm to 15 µm
|-
|style="background:silver; color:black"|
|style="background:LightGrey; color:black"|Film thickness accuracy
|style="background:WhiteSmoke; color:black"|
*±(0.5%+50Å)
|-
|style="background:silver; color:black"|
|style="background:LightGrey; color:black"|Index accuracy
|style="background:WhiteSmoke; color:black"|
*±0.001
|-
!style="background:silver; color:black" align="left"|Process parameter range
|style="background:LightGrey; color:black"|Wavelength range
|style="background:WhiteSmoke; color:black"|
Can operate at two different wavelength:
*633 nm
*1550 nm
|-
!style="background:silver; color:black" align="left"|Substrates
|style="background:LightGrey; color:black"|Batch size
|style="background:WhiteSmoke; color:black"|
*One sample at a time - all sample larger than 5x5 mm<sup>2</sup>sizes up to 6"
|-
|style="background:silver; color:black"|
| style="background:LightGrey; color:black"|Substrate material allowed
|style="background:WhiteSmoke; color:black"|
*In principle all materials
|- 
|}

==Comparison of the three methods==
For comparison of the three methods, see here: [[Specific Process Knowledge/Characterization/Measurement of film thickness and optical constants#Film_thickness_and_optical_constants_of_optical_transparent_films|Film thickness and optical constants of optical transparent films]]